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to and from a cell where a mobile device resides. As discussed in Section 4.7.2, the NSEI
identi¬es a group of frame relay permanent virtual circuits. The BVCI is used to identify
the particular cell. It should be noted that the BVCI has relevance only over the Gb
interface and that it will be mapped to the correct RLC/MAC identi¬er across the Abis
interface. As well as being used to identify a cell, at least one BVC is also required for
signalling purposes such as paging.
The BSSGP protocol actually provides a connectionless link between the SGSN and
BSS. The ¬‚ow control mechanism based on the ˜leaky bucket™ introduces QoS pro¬les,
and a cell (BVC) may have a queue and context in the SGSN and BSS. This queue
may be further subdivided for particular subscribers (identi¬ed by the TLLI). There are
three types of context prede¬ned: best effort, SMS and signalling, where data can be
transported over either the best effort or the SMS context. If it is transported over the
SMS context, then it will be transported with the QoS pro¬le which has been established
for SMS. The ¬‚ow control mechanism is only required in the downlink direction, since
buffers and link capacity in the uplink should be over-dimensioned to avoid loss of data
in this direction.
Figure 4.29 shows an example trace from a GPRS network. In this particular trace a
mobile device is requesting attachment to the network. Both the uplink attach request and
the downlink attach accept are shown. It can be seen that the mobile device provides a
great deal of information, including the QoS required and the encryption algorithms that
can be supported. It can also be seen that the attach request message sent with RLC/MAC
ARQ functionality (acknowledged mode) whereas the downlink attach accept message is
using the unacknowledged UNITDATA transfer over the RLC/MAC.
The trace in Figure 4.30 is again taken across the Gb interface and is a session man-
agement activate PDP context request. Again, it can be seen that in the uplink over the
RLC/MAC ARQ functionality is used whereas the downlink pdp context accept message
is using the UNITDATA transfer. Also transferred are the NSAPI and SAPI identi¬ers as
well as the requested QoS and the access point to which this request is for.
124 GENERAL PACKET RADIO SERVICE


UPLINK DOWNLINK
Conn:1 Line:1 TS:1 Hyperch:1984 kb/s
Conn:1 Line:1 TS:1 Hyperch:1984 kb/s
114 13:42:59.679
113 13:42:59.502
DL-UNITDATA
UL-UNITDATA
TLLI
TLLI
- Random TLLI
- Random TLLI
- Value: 52 67 34 DE
- Value: 52 67 34 DE
QoS Profile
QoS Profile
- bit rate : best effort
- bit rate : best effort
- precedence: Reserved(Low/Priority 3)
- precedence: Reserved/Unknown
- Radio Interface uses RLC/MAC-UNITDATA
- Radio Interface uses RLC/MAC ARQ
functionality
functionality
- The SDU contains data
- The SDU contains signalling
- LLC ACK/SACK not present
- LLC ACK/SAC present
PDU Lifetime
Cell Identifier
- 8.00 sec
- MCC : 211
MS Radio Access Capab.
- MNC : 77
GSM 900-P Access Technology Type
- LAC : 29 (1Dh)
- Length: 33 bits
- RAC : 161 (A1h)
- RF Power class: 1
- cell id value: 2 (2h)
- Encrypt. algorithm A5/1 available
Alignment Octets : FF FF FF
- Encrypt. algorithm A5/2 available
LLC-PDU
- Encrypt. algorithm A5/3 not available
ATTACH REQUEST (GPRS MM)
- Encrypt. algorithm A5/4 not available
MS Network Capability
- Encrypt. algorithm A5/5 not available
- Encryption algorithm GEA/1 available
- Encrypt. algorithm A5/6 not available
- SM capabilities via dedicated channels
- Encrypt. algorithm A5/7 not available
supported
- Controlled early Classmark Sending not
- SM capabilities via GPRS channels
implemented
supported
- PS capability not present
- Use of default alphabet over UCS2
- VGCS capability and notifications not
prefered
wanted
- Default value of phase 1
- VBS capability and notifications not
- The ME does not support SoLSA
wanted
- Mobile station supporting earlier
- GPRS Multislot Class: 6
versions of the protocol
- GPRS Ext. Dynamic Alloc. Capability not
Attach Type
implemented
- GPRS attach
- SMS Value: 5/4 timeslot
- No follow-on request pending
- SM Value: 2/4 timeslot
GPRS Ciphering Key Seq. Nr
- Spare ok
- value: 7 (07h)
DRX Parameters
DRX Parameter
- no DRX used by the MS
- no DRX used by the MS
- DRX cycle length coefficient not
- DRX cycle length coefficient not
specified by the MS
specified by the MS
- Split pg cycle on CCCH not supported
- Split pg cycle on CCCH not supported
- no non-DRX mode after transfer state
- no non-DRX mode after transfer state
TLLI
Mobile identity
- Random TLLI
- length: 8 (08h)
- Value: 52 67 34 DE
- IMSI: 211772000012345
LLC-PDU
Routing Area Id.
ATTACH ACCEPT (GPRS MM)
- Mobile Country Code: 000
Attach Result
- Mobile Network Code: 000
- GPRS only attached
- Location Area Code: 0 (0h)
Force to Standby
- Routing Area Code: 0 (00h)
- not indicated
MS Radio Access Capability
GPRS Timer
GSM 900-P Access Technology Type
- Value: 54 min
- Length: 33 bits
Radio Priority
- RF Power class: 1
- Priority level 3
- Encrypt. algorithm A5/1 available
Routing Area Id.
- Encrypt. algorithm A5/2 available
- Mobile Country Code: 211
- Encrypt. algorithm A5/3 not available
- Mobile Network Code: 77
- Encrypt. algorithm A5/4 not available
- Location Area Code: 29 (1Dh)
- Encrypt. algorithm A5/5 not available
- Routing Area Code: 161 (A1h)
- Encrypt. algorithm A5/6 not available
GPRS Timer
- Encrypt. algorithm A5/7 not available
- Value: 44 sec
- Controlled early Classmark Sending not
P-TMSI
implemented
- length: 5 (05h)
- PS capability not present
- TMSI/P-TMSI: c00003b6
- VGCS capability and notifications not
wanted
- VBS capability and notifications not
wanted
- GPRS Multislot Class: 6
- GPRS Ext. Dynamic Alloc. Capability not
implemented
- SMS Value: 5/4 timeslot
- SM Value: 2/4 timeslot
- Spare ok




Figure 4.29 Attach trace across Gb. Reproduced by permission of NetHawk Oyj
4.7 GB INTERFACE PROTOCOLS 125


UPLINK DOWNLINK
Conn:1 Line:1 TS:1 Hyperch:1984 kb/s
Conn:1 Line:1 TS:1 Hyperch:1984 kb/s
121 13:43:10.119
120 13:43:10.092
DL-UNITDATA
UL-UNITDATA
TLLI
TLLI
- Local TLLI
- Local TLLI
- Value: 52 67 34 DE
- Value: 52 67 34 DE
QoS Profile
QoS Profile
- bit rate : best effort
- bit rate : best effort
- precedence: Normal/Priority 2
- precedence: Reserved(Low/Priority 3)
- Radio Interface uses RLC/MAC-UNITDATA
- Radio Interface uses RLC/MAC ARQ
functionality
functionality
- The SDU contains data
- The SDU contains signalling
- LLC ACK/SACK not present
- LLC ACK/SAC present
PDU Lifetime
Cell Identifier
- 8.00 sec
- MCC : 211
MS Radio Access Capab.
- MNC : 77
GSM 900-P Access Technology Type
- LAC : 29 (1Dh)
- Length: 33 bits
- RAC : 161 (A1h)
- RF Power class: 1
- cell id value: 2 (2h)
- Encrypt. algorithm A5/1 available
Alignment Octets : FF FF FF
- Encrypt. algorithm A5/2 available
LLC-PDU
- Encrypt. algorithm A5/3 not available
ACT. PDP CONTEXT REQUEST (GPRS SM)
- Encrypt. algorithm A5/4 not available
Network Serv. Access Point Id
- Encrypt. algorithm A5/5 not available
- NSAPI 5
- Encrypt. algorithm A5/6 not available
LLC Serv. Access point Id
- Encrypt. algorithm A5/7 not available
- SAPI 3
- Controlled early Classmark Sending not
Quality of Service
implemented
- length: 3 (03h)
- PS capability not present
- Reliab. class: Unack. GTP and LLC
- VGCS capability and notifications not
Ack. RLC Protected data
wanted
- Delay class: Delay class 1
- VBS capability and notifications not
- Precedence class: High priority
wanted
- Peak throughput: Up to 2 000
- GPRS Multislot Class: 6
octet/s
- GPRS Ext. Dynamic Alloc. Capability not
- Mean throughput: 200 octet/h
implemented
Packet Data Protocol Address
- SMS Value: 5/4 timeslot
- Length: 6 (06h)
- SM Value: 2/4 timeslot
- PDP type organisation: IETF
- Spare ok
allocated address
DRX Parameters
- PDP type number: IPv4
- no DRX used by the MS
- Address: 10.1.21.2
- DRX cycle length coefficient not specified
Access Point Name

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